Construction machine

ABSTRACT

A construction machine in which an electrical unit can be reliably cooled at low cost by effectively utilizing an intake pipe connected to an intake port of an engine. This construction machine includes: an engine; and a hood covering the engine, wherein a space inside the hood has a placement space in which an electrical unit is placed and which communicates with outside air, and a distal-end opening of an intake pipe connected to an inlet port of the engine is disposed in the placement space to cause outside air sucked into the intake pipe due to a suction pressure occurred in the intake pipe to pass through the placement space to form a cooling air path in the placement space.

TECHNICAL FIELD

The present invention relates to a construction machine, andspecifically to a construction machine provided with an electrical unitand a structure for cooling the electrical unit.

BACKGROUND ART

Heretofore, Patent Literatures 1 and 2 (hereinafter, referred to as PTLs1 and 2) have disclosed, as one embodiment of a construction machine, astructure for cooling an electrical component placed in an engine room.Specifically, PTL 1 discloses a structure in which a compressor isinterlocked and coupled to an engine mounted in an engine room.According to this structure, the compressor is driven to compress airsucked thereinto from the outside, and the compressed air dischargedfrom the compressor is blown to an electrical component for cooling theelectrical component. PTL 2 discloses a structure in which outside airtaken into an intake chamber through an intake duct is blown toward anengine by a blower fan. In addition, an electrical component coveraccommodating an electrical component in its inside has an upper portionincluding an intake hole communicating with the intake chamber and alower portion including an exhaust hole communicating with the inside ofthe intake duct. This provides an air flow path for causing air to flowalong the electrical component for cooling the electrical component.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Application Laid-Open No. 2003-328769

PTL 2: Japanese Patent Application Laid-Open No. 2015-140156

SUMMARY OF INVENTION Technical Problem

Unfortunately, however, the structure according to PTL 1 requires thecompressor additionally. Meanwhile, although the structure according toPTL 2 does not require any additional blower fan because the blower fanused to cool the engine is also used to cool the electrical component,designing of the air flow path is complicated, which may lead to anincrease in cost. In addition, PTLs 1 and 2 involve disadvantages asbelow. That is, devices such as an electrical component to be placed ina space inside a hood have a working temperature range that is specifiedat a certain temperature or lower. However, the space inside the hoodoften has a high temperature. Thus, in order to place such devices inthe space inside the hood while satisfying the working temperaturerange, a countermeasure is taken by placing the electrical component farfrom the engine and/or by using a large amount of heat insulatingmaterials to reduce heat conducted to the electrical component. However,the countermeasure by placing the electrical component far from theengine results in a complicated part shape of the electrical component.Consequently, manufacturing cost of the construction machine is greatlyaffected by the cost of the electrical component, disadvantageously.Meanwhile, the countermeasure by using the heat insulating materialsalso requires the cost of the heat insulating materials, and thusrequires the cost of the heat insulating materials enough to satisfy thetemperature range, disadvantageously.

In view of the circumstances described above, some aspects of thepresent invention have an object to provide a construction machine inwhich an electrical unit can be reliably cooled at low cost byeffectively utilizing an intake pipe connected to an inlet port of anengine.

Solution to Problem

A first aspect of the present invention provides a construction machineincluding:

an engine; and

a hood covering the engine, wherein

a space inside the hood has a placement space in which an electricalunit is placed and which communicates with outside air, and

a distal-end opening of an intake pipe connected to an inlet port of theengine is disposed in the placement space to cause outside air suckedinto the intake pipe due to a suction pressure occurred in the intakepipe to pass through the placement space to form a cooling air path inthe placement space.

A second aspect of the present invention is the first aspect of thepresent invention configured such that

an intake duct having an outside-air inlet port through which outsideair is drawn and a communication port disposed downward of theoutside-air inlet port is placed in the placement space,

the distal-end opening of the intake pipe is disposed upward of thecommunication port to form the cooling air path that is circuitous tocause the outside air drawn through the outside-air inlet port to passthrough the intake duct, to exit from the intake duct through thecommunication port, and to be drawn upward into the distal-end openingof the intake pipe, and

the electrical unit is placed in a downstream portion of the cooling airpath, the downstream portion being located outside of the intake duct.

A third aspect of the present invention is the second aspect of thepresent invention configured such that

the placement space is a part of the space inside the hood, the partbeing partitioned by a partitioning wall serving as an inner wall placedin the space inside the hood and by a part of the hood serving as anouter wall,

the intake duct is shaped in a box which is vertically long in atop-and-bottom direction and which is constituted by a duct main pieceplaced in the placement space and by a part of the hood serving as anouter side wall,

the outside-air inlet port is formed in the part of the hood serving asthe outer side wall so that the outside-air inlet port coincides with anupper portion of the duct main piece,

the communication port is formed in a lower portion of the duct mainpiece, and

the distal-end opening of the intake pipe is penetrated through an upperportion of the partitioning wall to be disposed in the placement space.

A fourth aspect of the present invention is the second or third aspectof the present invention configured such that

the communication port is opened toward the electrical unit placed inthe placement space.

A fifth aspect of the present invention is any one of the second tofourth aspects of the present invention configured such that

the intake duct has a bottom including a draining hole for dischargingrainwater having entered the intake duct through the outside-air inletport.

Advantageous Effects of Invention

According to the aspects of the present invention, it is possible toreliably cool the electrical unit at low cost by effectively utilizingthe intake pipe connected to the inlet port of the engine.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A left side view of a construction machine according to oneembodiment of the present invention.

FIG. 2 An explanatory plane view of the construction machine accordingto the one embodiment of the present invention.

FIG. 3 A front view of the construction machine according to the oneembodiment of the present invention.

FIG. 4 A perspective view of a prime motor unit according to the oneembodiment of the present invention, viewed from the top right.

FIG. 5 A perspective view, viewed from the front top right, of the primemotor unit according to the one embodiment of the present invention fromwhich an openable-side ceiling and right side wall is removed.

FIG. 6 A perspective view, viewed from the rear top left, of the primemotor unit according to the one embodiment of the present invention fromwhich a fixed-side ceiling wall and the openable-side ceiling and rightside wall are removed.

FIG. 7 A perspective view, viewed from the front top right, of a rearright portion of the prime motor unit according to the one embodiment ofthe present invention from which the fixed-side ceiling wall and theopenable-side ceiling and right side wall are removed.

FIG. 8 An explanatory perspective view, viewed from the front top right,of the rear right portion of the prime motor unit according to the oneembodiment of the present invention from which the fixed-side ceilingwall and the openable-side ceiling and right side wall are removed.

FIG. 9 An explanatory right-side view of a cooling air path in aplacement space according to the one embodiment of the presentinvention.

FIG. 10 An explanatory front view of the cooling air path in theplacement space according to the one embodiment of the presentinvention.

FIG. 11 An explanatory perspective view of the cooling air path in theplacement space according to the one embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

With reference to the drawings, embodiments of the present inventionwill be described. The reference sign “A” shown in FIGS. 1 to 3 denotesa construction machine A of the present embodiment. First, an overallconfiguration of the construction machine A will be described.Thereafter, a characteristic configuration of the construction machine Awill be described.

[Description of Overall Configuration of Construction Machine]

As illustrated in FIGS. 1 to 3, the construction machine A includes aturning base mount 11 laid across a pair of left and right travelingunits 10 of crawler-type. On the turning base mount 11, a turning base12 is turnably mounted. On the turning base 12, a load carrier 13 ismounted. In addition, a dump cylinder 14 is interposed between theturning base 12 and the load carrier 13 such that the load carrier 13can be tilted by the dump cylinder 14. The load carrier 13 has a rearlower portion provided with a tilting fulcrum 37 for the load carrier13. The turning base mount 11 is provided with an overhung machine-bodyframe 15 extending forward in an overhung state. A floor 16 is spreadover a left side of the overhung machine-body frame 15, and an operationunit 17 is mounted on the floor 16. Meanwhile, a prime motor unit 18 isplaced on a right side of the overhung machine-body frame 15. A roof 19is provided vertically above the operation unit 17 via a roof support38.

The traveling unit 10 on the left side includes a traveling unit frame20 extending in a front-and-rear direction and having a front endprovided with a left hydraulic motor ML for traveling. The lefthydraulic motor ML for traveling includes a drive shaft 21 to which adriving wheel 22 is attached. The traveling unit frame 20 has a rear endto which a driven wheel 24 is attached via a driven-wheel support shaft23. A crawler 25 is wound around the driving wheel 22 and the drivenwheel 24. A rolling wheel 26 is attached to an intermediate portion ofthe traveling unit frame 20 such that the rolling wheel 26 supports theintermediate portion of the crawler 25. The traveling unit 10 on theright side has a similar configuration to that of the traveling unit 10on the left side, and includes a traveling unit frame 20 having a frontend provided with a right hydraulic motor MR for traveling.

By causing the left and right hydraulic motors ML and MR for travelingto rotate in a forward direction, it is possible to cause the machinebody to travel forward (to travel leftward in FIG. 1). Meanwhile, bycausing the left and right hydraulic motors ML and MR for traveling torotate in a reverse direction, it is possible to cause the machine bodyto travel backward (to travel rightward in FIG. 1). By causing the left(right) hydraulic motor ML (MR) for traveling to rotate in the forwarddirection and stopping the right (left) hydraulic motor MR (ML) fortraveling, it is possible to cause the machine body to make a turn(pivot turn) rightward (leftward). By causing the left (right) hydraulicmotor ML (MR) for traveling to rotate in the forward direction andcausing the right (left) hydraulic motor MR (ML) for traveling to rotatein the reverse direction, it is possible to cause the machine body tomake a sharp turn (spin turn) rightward (leftward) at that place.

The turning base mount 11 is provided with a hydraulic motor Mt forturning. The hydraulic motor Mt for turning includes a drive shaft (notillustrated) to which a pinion gear (not illustrated) is attached. Theturning base 12 is provided with an annulus gear (not illustrated)engaged with the pinion gear. By causing the drive shaft of thehydraulic motor Mt for turning to rotate in a forward or reversedirection, it is possible to cause the turning base 12 to turncounterclockwise or clockwise as appropriate via the pinion gear and theannulus gear.

The load carrier 13 is shaped in a box opened upward. In addition, theload carrier 13 has, in a rear portion of a bottom of the load carrier13, an inclined bottom 30 that is lower in the front and higher in therear. The load carrier 13 has left and right inclined walls 31 and 32,which are located in left and right front portions of the load carrier13, respectively. Each of the inclined walls 31 and 32 is inclined suchthat, in a plan view, a front end of the inclined wall is located inwardand a rear end of the inclined wall is located outward. With the loadcarrier 13 having such a shape, it is possible to avoid a collision ofthe left or right inclined wall 31 or 32 of the load carrier 13 againstthe operation unit 17 or the prime motor unit 18 when the load carrier13 is turned leftward or rightward integrally with the turning base 12.

By elongating the dump cylinder 14 with the rear end of the load carrier13 facing rearward, it is possible to tilt the load carrier 13 rearwardabout the tilting fulcrum 37. Consequently, a load in the load carrier13 can be dumped rearward. By turning, by 90 degrees via the turningbase 12, the load carrier 13 facing backward, the rear end of the loadcarrier 13 is caused to face leftward (rightward). By elongating thedump cylinder 14 in this state, it is possible to tilt the load carrier13 about the tilting fulcrum 37 so that the load carrier 13 is broughtinto a state in which the left side of the load carrier 13 is lower andthe right side of the load carrier 13 is higher (the right side of theload carrier 13 is lower and the left side of the load carrier 13 ishigher). Consequently, a load in the load carrier 13 can be dumpedleftward (rightward).

The operation unit 17 includes a support case 40 for supporting anoperator's seat 41, the support case 40 being located in a centerportion of the floor 16. The support case 40 has a left side on which aleft control part 42 is attached in a standing manner such that the leftcontrol part 42 extends forward and upward. The left control part 42includes a left control case 45 and a traveling lever 47 protrudingforward and upward from an upper end of the left control case 45.

The left control case 45 has an upper surface including an intermediateportion on which a left armrest 44 is attached in a standing manner. Theleft armrest 44 is located behind the traveling lever 47. The leftarmrest 44 is configured to allow an operator sitting on the operator'sseat 41 to place an elbow-side portion of his/her forearm on the leftarmrest 44 and to grasp an upper-end grip portion of the traveling lever47 with his/her hand. Consequently, the operator can tilt the travelinglever 47 forward, rearward, leftward, or rightward.

The support case 40 has a right side on which a right control part 52 isattached in a standing manner such that the right control part 52extends forward and upward. The right control part 52 includes a rightcontrol case 55 and a turning-and-dumping lever 57 protruding forwardand upward from an upper end of the right control case 55.

The right control case 55 has an upper surface including an intermediateportion on which a right armrest 54 is attached in a standing manner.The right armrest 54 is located behind the turning-and-dumping lever 57.The right armrest 54 is configured to allow the operator sitting on theoperator's seat 41 to place an elbow-side portion of his/her forearm onthe right armrest 54 and to grasp an upper-end grip portion of theturning-and-dumping lever 57 with his/her hand. Consequently, theoperator can tilt the turning-and-dumping lever 57 forward, rearward,leftward, or rightward.

With such a configuration, the operator sitting on the operator's seat41 grasps, with his/her left hand, the traveling lever 47 protrudingfrom the left control case 45, and grasps, with his/her right hand, theturning-and-dumping lever 57 protruding from the right control case 55.Thus, the operator can operate the lever 47 and/or 57 as appropriate.

As illustrated in FIGS. 5 and 6, the prime motor unit 18 includes, on aright side portion of the overhung machine-body frame 15, an engine (inthe present embodiment, a diesel engine) E, a heat exchange means 58, agroup of pumps 60, a fuel tank 70, an electrical unit 80, and the like,which are covered with a hood 33.

As illustrated also in FIG. 6, the engine E is mounted on a portion ofthe overhung machine-body frame 15, the portion corresponding to a leftside portion of a space inside the hood 33. In this portion, the engineE is disposed to extend in the front-and-rear direction. The engine Ehas an inlet port 71 connected to a proximal end of an intake pipe 72.The intake pipe 72 has an intermediate portion provided with an aircleaner 73. Outside air is sucked through a distal-end opening 74 of theintake pipe 72, and the outside air is then sucked to pass through theair cleaner 73 so that the outside air is cleaned therein. Thereafter,the outside air thus cleaned is supplied to the engine E through theinlet port 71. During this process, a suction pressure (negativepressure) occurs in the intake pipe 72 due to the inlet port 71. Thisallows the outside air to be sucked through the distal-end opening 74.The engine E has an exhaust port (not illustrated) connected to aproximal end of an exhaust pipe 76. The exhaust pipe 76 has anintermediate portion provided with a diesel particulate filter (DPF) 75that is an exhaust gas purification device. Particulate matters (PM) inan exhaust gas emitted from the exhaust port of the engine E arecollected (caught by filtering) and reduced by a filter integrated inthe DPF 75. Thereafter, the exhaust gas is discharged through adistal-end opening of the exhaust pipe 76 to the outside of the hood 33.The filter in the DPF 75 is, e.g., ceramics or a metallic porous bodyhaving a large number of holes each having a diameter of approximately10 micrometers, being capable of removing minute particles by filtering,and having high durability. When the particulate matters (PM)accumulated inside the filter are burnt by high-temperature heat of,e.g., 600° C. or higher, the filter regains its function.

The air cleaner 73 and the DPF 75, which are located behind and abovethe engine E, are arranged vertically in parallel to each other withtheir longitudinal directions coinciding with a left-and-rightdirection. In front of the engine E, the heat exchange means 58 having aheat exchanging function for cooling the engine E is provided. The heatexchange means 58 includes components such as a radiator and a suctionfan. The heat exchange means 58 is disposed behind a front grille 66(described later) such that the heat exchange means 58 faces the frontgrille 66. The heat exchange means 58 sucks outside air through thefront grille 66 by the suction fan interlocked with the engine E, andgenerates water for cooling the engine E.

As illustrated in FIGS. 1 to 3, the group of pumps 60, which is locatedbehind the engine E, includes a right pump PR for traveling, a left pumpPL for traveling, a charging pump Pc, and a pump Ptd for turning anddumping that coupled in series to a drive shaft (not illustrated) of theengine E such that these pumps are interlocked with the drive shaft. Theleft pump PL for traveling is in fluid connection with the lefthydraulic motor ML for traveling via hydraulic piping for traveling (notillustrated), and whereby a hydrostatic continuously variabletransmission on the left side is constituted. The right pump PR fortraveling is in fluid connection with the right hydraulic motor MR fortraveling via hydraulic piping for traveling, and whereby a hydrostaticcontinuously variable transmission on the right side is constituted. Thehydrostatic continuously variable transmissions on the left and rightsides are interlocked and connected to the driving wheels 22 of thetraveling units 10 on the left and right sides, respectively. Thehydrostatic continuously variable transmissions on the left and rightsides allow their corresponding traveling units 10 to travel whileseamlessly changing speeds of the traveling units 10. The pump Ptd forturning and dumping is in fluid connection with the hydraulic motor Mtfor turning and the dump cylinder 14 in parallel via hydraulic pipingfor turning and dumping (not illustrated).

As illustrated in FIGS. 5 and 6, the fuel tank 70 has a shape being longin the front-and-rear direction and being thin in the left-and-rightdirection. In addition, the fuel tank 70 is placed on a portion of theoverhung machine-body frame 15, the portion corresponding to a frontright portion of the space inside the hood 33.

As illustrated also in FIG. 7, the electrical unit 80 is placed on aportion of the overhung machine-body frame 15, the portion correspondingto a rear right portion of the space inside the hood 33. As illustratedin FIGS. 8 to 11, the electrical unit 80 includes electrical componentssuch as a controller 82, a relay 83, and a fuse 84. The controller 82has a function of controlling, e.g., a fuel injection amount and a fuelinjection timing of the engine E and a timing at which the filter of theDPF 75 is burnt to regain its function.

As illustrated also in FIGS. 4 to 7, the hood 33 has a cap-shape whichis opened downward and which is constituted by a front wall 61, a rearwall 62, a left side wall (inner wall) 63, a fixed-side ceiling wall 64constituting a left side portion of a ceiling wall, and an openable-sideceiling and right side wall (openable lid) 65 constituting a right sideportion of the ceiling wall (openable-side ceiling wall 65 a) and aright side wall (outer side wall) 65 b.

The front wall 61 has the front grille 66 through which outside air fromthe front is drawn. The rear wall 62 has a louver 67 through whichexhaust heat and/or the like is discharged to the rear, i.e., to theoutside of the hood 33. The left side wall (inner wall) 63 has a centerupper portion in which a recess 34 for avoiding interference is formed.The right control part 52 is disposed close to the left side wall 63such that interference of the right control part 52 with respect to theleft side wall 63 is avoided by the recess 34. A horizontal supportpiece 69, which extends in the front-and-rear direction, is horizontallylaid over a left side portion between the front wall 61 and the rearwall 62. The fixed-side ceiling wall 64 is fixedly and horizontally laidover a space between upper ends of the front wall 61, the rear wall 62,and the left side wall 63 and over a left side portion of an uppersurface of the horizontal support piece 69. In the openable-side ceilingand right side wall 65, a left edge of the openable-side ceiling wall 65a is pivotally supported at a right side portion of the upper surface ofthe horizontal support piece 69 via a pivot support body (notillustrated), and the right side wall 65 b has a lower portion providedwith an opening-and-closing control part 68 (see FIG. 4). Thus, theopenable-side ceiling and right side wall 65 functions as an openablelid. By operating the opening-and-closing control part 68, it ispossible to open the openable-side ceiling and right side wall 65 upwardso that the openable-side ceiling surface and the right side surface ofthe hood 33 can be opened simultaneously. An operational panel part 35is provided above the fixed-side ceiling wall 64.

[Description of Characteristic Configuration of Construction Machine]

Next, with reference to FIGS. 4 to 11, the following will describe acharacteristic configuration of the construction machine A configured asdescribed above. Specifically, the space inside the hood 33 covering theengine E has a placement space S in which the electrical unit 80 isplaced and which communicates with outside air. The distal-end opening74 of the intake pipe 72 connected to the inlet port 71 of the engine Eis placed in the placement space S to cause outside air sucked into theintake pipe 72 due to a suction pressure (negative pressure) occurred inthe intake pipe 72 to pass through the placement space S to form acooling air path W in the placement space S. In the cooling air path W,at least part (in the present embodiment, the relay 83 and the fuse 84)of the electrical unit 80 is placed. As a result, the placement space Sis cooled by the cooling air, so that the electrical unit 80 is cooleddirectly inside the cooling air path W or indirectly outside the coolingair path W.

Here, the space inside the hood 33 has a high atmospheric temperaturedue to heat generated by the engine E. In order to deal with this,outside air is introduced into the placement space S, so that thecooling air path W for cooling the placement space S is formed. Deviceshaving a working temperature range that is specified to be at a certaintemperature or lower are collected in one place in the placement spaceS, so that these devices constitute the electrical unit 80. By disposingat least part of the electrical unit 80 in the cooling air path W, theelectrical unit 80 can be reliably cooled by the cooling air.Consequently, an ambient temperature of the electrical unit 80 can belowered to a temperature of 60° C. or less, and thus it is possible toprevent a situation that the electrical components constituting theelectrical unit 80 erroneously operate due to heat. Furthermore, sincethe temperature in the placement space S can be made similar or equal tothat of the outside air, it is possible to reduce the number of heatinsulating materials to be used to thermally insulate the electricalcomponents.

In the placement space S, an intake duct 85 having an outside-air inletport 86 through which outside air is drawn and a communication port 87disposed downward of the outside-air inlet port 86 is placed. Thedistal-end opening 74 of the intake pipe 72 is disposed upward of thecommunication port 87 to form the cooling air path W that is circuitousto cause the outside air drawn through the outside-air inlet port 86 topass through the intake duct 85, to exit from the intake duct 85 throughthe communication port 87, and to be drawn upward into the distal-endopening 74 of the intake pipe 72. The electrical unit 80 is placed in adownstream portion of the cooling air path W, the downstream portionbeing located outside of the intake duct 85 and being in the placementspace S. Furthermore, the electrical unit 80 is located upward from thecommunication port 87.

The placement space S is a part of the space (engine room) inside thehood 33, the part being partitioned by a partitioning wall 100 servingas an inner wall placed in the space inside the hood 33 and by a part ofthe hood 33 serving as an outer wall.

The intake duct 85 is shaped in a box (bottomed cylinder) which isvertically long in a top-and-bottom direction and which is constitutedby a duct main piece 88 placed in the placement space S and by a part ofthe hood 33 serving as an outer side wall. Specifically, the intake duct85 includes, as one of constituent elements thereof, the right side wall65 b of the openable-side ceiling and right side wall 65 of the hood 33,and is shaped in a thin box extending in the top-and-bottom directionalong an inner surface of the right side wall 65 b. Namely, the intakeduct 85 is a part of the placement space S partitioned by the duct mainpiece 88 facing the right side wall 65 b of the hood 33, and is asubstantially flat space formed along an inner wall surface of the rightside wall 65 b and between the right side wall 65 b and the duct mainpiece 88 facing each other. The intake duct 85 is constituted by theduct main piece 88 whose right end face is in contact with the innersurface of the right side wall 65 b, the duct main piece 88 being shapedin a thin cap (tray) that is opened upward and rightward.

The outside-air inlet port 86 is formed in the part of the hood 33serving as the outer side wall so that the outside-air inlet port 86coincides with an upper portion of the duct main piece 88. Specifically,the outside-air inlet port 86 is located upward of the intake duct 85,and is formed in the right side wall 65 b of the openable-side ceilingand right side wall 65. The communication port 87 is formed in a lowerportion of a left side wall of the duct main piece 88, and is openedtoward a side on which the electrical unit 80 is placed. Namely, in theplacement space S, the communication port 87 allows a lower portion ofthe intake duct 85 partitioned by the duct main piece 88 to communicatewith a part of the space opposite to the intake duct 85 across the ductmain piece 88.

The duct main piece 88 has a bottom including a draining hole 89 (seeFIG. 9) for discharging rainwater and/or the like having entered theintake duct 85 through the outside-air inlet port 86. The draining hole89 is located downward of the communication port 87. The inner surfaceof the right side wall 65 b has a rear lower portion provided with awater discharging part 91 shaped in a box whose right side is opened.The draining hole 89 is connected to a proximal end (upper end) of adraining pipe 90 at a lower side of the duct main piece 88. Meanwhile,the water discharging part 91 is connected to a distal end (lower end)of the draining pipe 90 extended downward. The right side wall 65 b hasa discharge hole 92 at a location coinciding with a plane of the openingof the water discharging part 91. Through the discharge hole 92,rainwater and/or the like is discharged to the outside of the machine.In the above-described manner, the intake duct 85, the draining pipe 90,and the water discharging part 91 are attached integrally to theopenable-side ceiling and right side wall 65.

To be more specific, the placement space S in which the electrical unit80 is placed is located in a right rear portion of the space inside thehood 33, and is formed by the partitioning wall 100 provided on theoverhung machine-body frame 15 in a standing manner, the rear wall 62,and the openable-side ceiling and right side wall 65. Closing theopenable-side ceiling and right side wall 65 brings the placement spaceS into a closed state. Meanwhile, opening the openable-side ceiling andright side wall 65 brings the placement space S into a state in which anupper side and a right side of the placement space S are opened.

The partitioning wall 100 is supported in a standing state by a support81 attached to the overhung machine-body frame 15 in a standing manner.The partitioning wall 100 is constituted by a partitioning-wall frontpiece 102 standing to face the fuel tank 70, a partitioning-wall sidepiece 104 standing to face the engine E with a front edge of thepartitioning-wall side piece 104 being connected to a left edge of thepartitioning-wall front piece 102, and a partitioning-wall rear piece106 standing with a front edge of the partitioning-wall rear piece 106being connected to a rear edge of the partitioning-wall side piece 104and a rear edge of the partitioning-wall rear piece 106 being in contactwith a right side of the rear wall 62. The partitioning-wall front piece102, the partitioning-wall side piece 104, and the partitioning-wallrear piece 106 have respective upper edges formed along an inner surfaceof the openable-side ceiling and right side wall 65 being in a closedstate. In addition, a wall sealing material 108 is attached to theseupper edges and to a right edge of the partitioning-wall front piece102. Consequently, the inner surface of the openable-side ceiling andright side wall 65 being in a closed state is in close contact with thepartitioning wall 100 via the wall sealing material 108.

To the partitioning-wall side piece 104, a left side surface of thecontroller 82, which is thin in the left-and-right direction, isattached such that the left side surface of the controller 82 and thepartitioning-wall side piece 104 face each other. A ceiling surface 110is stretched over a space above the partitioning-wall front piece 102,the partitioning-wall side piece 104, and the partitioning-wall rearpiece 106. The ceiling surface 110 has a left side portion that ishorizontal and a right side portion that is downwardly inclined towardthe right side. Below the ceiling surface 110, a suspended support 112is disposed. The suspended support 112 is located on the right side ofthe controller 82, and has side surfaces respectively facing rightwardand leftward. The suspended support 112 has a plate-shape, and issuspended vertically downward. On the right side surface of thesuspended support 112, components such as the relay 83 and the fuse 84are attached and arranged at intervals in the top-and-bottom direction.A battery 114 is placed on a portion of the overhung machine-body frame15, the portion being inside the placement space S. A distal end of theintake pipe 72 penetrates through an upper front portion of thepartitioning-wall side piece 104 such that the distal end of the intakepipe 72 extends horizontally from the left side to the right sidedirectly below the ceiling surface 110. In addition, the distal-endopening 74 is opened toward the right side, at a location just in frontof the suspended support 112. A first harness 127 is provided above thebattery 114, and a second harness 128 is provided to extend upward froma position in front of the battery 114.

The ceiling surface 110 has an upper surface from which a pair of frontand rear upper locking pins 116 is protruded. The upper locking pins 116are engaged with a pair of front and rear locking holes 120 formed in anupper edge portion of an upper hung screen 118 for waterproofing. Theupper hung screen 118 is made of a waterproof material and is shaped ina sheet having a width substantially identical to a width of theplacement space S in the front-and-rear direction. The upper hung screen118 is suspended at a location on the right side of components such asthe relay 83 and the fuse 84. The upper hung screen 118 has a lower edgepositioned in the vicinity of an upper edge of the communication port87.

The right side surface of the suspended support 112 is provided with apair of front and rear lower locking pins 122 protruding therefrom. Alower hung screen 124 for waterproofing is locked and supported by thelower locking pins 122. The lower hung screen 124 has an upper edge inwhich a pair of front and rear lower locking holes 126 is formed. Thelower locking holes 126 are respectively engaged with the lower lockingpins 122. The lower hung screen 124 is made of a waterproof material andis shaped in a sheet having a width substantially identical to the widthof the placement space S in the front-and-rear direction. The lower hungscreen 124 is suspended to cover a portion of the battery 114, theportion extending from a right side portion of an upper surface of thebattery 114 to an upper portion of a right side surface of the battery114.

A lower portion of the upper hung screen 118 and an upper portion of thelower hung screen 124 are spaced apart at a certain interval D in theleft-and-right direction (see FIG. 10), and are disposed to overlap eachother in the left-and-right direction. Consequently, the downstreamportion of the cooling air path W extending in top-and-bottom directionis formed. Thus, outside air drawn through the communication port 87 isguided inward and upward by an intermediate portion of the lower hungscreen 124. The outside air thus guided inward and upward is guidedvertically upward by the lower portion of the upper hung screen 118 andthe upper portion of the lower hung screen 124. The outside air thusguided vertically upward is guided further upward by the upper hungscreen 118. Consequently, the outside air is reliably sucked into thedistal-end opening 74 of the intake pipe 72. Since the electrical unit80 is disposed in the downstream portion of the cooling air path Wextending in the top-and-bottom direction, the electrical unit 80 iscooled by the outside air guided upward. Particularly, since the relay83 and the fuse 84 are disposed between the intake duct 85 into whichthe outside air is taken and the distal-end opening 74 of the intakepipe 72 into which the outside air is sucked when viewed in the frontview illustrated in FIG. 10, the relay 83 and the fuse 84 are reliablycooled. Meanwhile, although the controller 82 is disposed leftward ofthe distal-end opening 74 of the intake pipe 72 into which the outsideair is sucked, the controller 82 is reliably cooled, since the whole ofthe placement space S serves as the cooling air path W due to the flowof the outside air.

The duct main piece 88 of the intake duct 85 is constituted by a ductfront wall 88 a extending in the top-and-bottom direction and having anarrow width in the left-and-right direction, a duct side wall 88 bhaving a front edge connected to a left side edge of the duct front wall88 a and having a pentagonal shape in a side view, a duct rear wall 88 chaving a left side edge connected to a rear edge of the duct side wall88 b, extending in the top-and-bottom direction, and having a narrowwidth in the left-and-right direction, and a duct bottom 88 d having aleft side edge connected to a lower edge of the duct side wall 88 b,extending in the front-and-rear direction, and having a narrow width inthe left-and-right direction. The duct rear wall 88 c is long and has alower edge located downward of a lower edge of the duct front wall 88 a.The duct side wall 88 b has the lower edge inclined to be higher in thefront and lower in the rear, so that the duct bottom 88 d, which isconnected to the lower edge of the duct side wall 88 b, has an inclinedposture with which the duct bottom 88 d becomes higher in the front andlower in the rear. The duct bottom 88 d has a front edge connected to alower edge of the duct front wall 88 a, and has a rear edge connected toa lower edge of the duct rear wall 88 c. The duct front wall 88 a andthe duct rear wall 88 c have right edges to which a front-wall ductsealing material 130 and a rear-wall duct sealing material 131 areattached, respectively. The duct bottom 88 d has a right edge to which,except for a rear edge thereof, a bottom duct sealing material 132 isattached. Thus, a space is given between a lower edge of the rear-wallduct sealing material 131 and a rear edge of the bottom duct sealingmaterial 132.

The duct side wall 88 b has a right side surface including anintermediate portion provided with a rainwater guide piece 140protruding therefrom. The rainwater guide piece 140 extends in thefront-and-rear direction, and is inclined to be lower in the front andhigher in the rear. Consequently, along an upper surface of therainwater guide piece 140, rainwater is guided to flow downward. Thecommunication port 87 is located in a lower portion of the duct sidewall 88 b, which is located downward of the rainwater guide piece 140.At the location, the communication port 87, which is shaped in atriangle, is opened in the left-and-right direction. The communicationport 87 has an upper edge that is horizontal and a lower edge that isinclined along the duct bottom 88 d.

To the right side wall 65 b of the openable-side ceiling and right sidewall 65, a pair of front and rear attachment brackets 142 extending inthe top-and-bottom direction is attached. From the left side of the ductside wall 88 b, male screw bolts 146 are penetrated through female screwbolts 144 attached to the attachment brackets 142, and the male screwbolts 146 are screwed with the female screw bolts 144. Consequently, theduct main piece 88 is attached to the right side wall 65 b, so that theintake duct 85 is formed. At this time, the front-wall, rear-wall, andbottom duct sealing materials 130, 131, and 132 attached to the rightedges of the duct front wall 88 a, the duct rear wall 88 c, and the ductbottom 88 d are pressed onto the right side wall 65 b of theopenable-side ceiling and right side wall 65 so as to be deformed.Consequently, the front-wall, rear-wall, and bottom duct sealingmaterials 130, 131, and 132 are in close contact with the right sidewall 65 b. The right side wall 65 b has an upper portion including theoutside-air inlet port 86. The outside-air inlet port 86 includesmultiple outside-air inlet ports (in the present embodiment, sevenoutside-air inlet ports) each of which is shaped in a vertically longrectangle and which are arranged at intervals in the front-and-reardirection. The duct bottom 88 d, which is inclined to be higher in thefront and lower in the rear, has a rear portion including the draininghole 89.

With the intake duct 85 configured as above, an internal pressure of theplacement space S is at a negative pressure due to the distal-endopening 74 of the intake pipe 72 connected to the inlet port 71 of theengine E. This provides an upstream portion of the cooling air path Walong which outside air is taken through the outside-air inlet port 86,the outside air is guided to flow downward, and the outside air flowsinto the placement space S through the communication port 87. In theplacement space S, the downstream portion of the cooling air path W isprovided as described above, and thus the electrical unit 80 is cooledby cooling air. During this, rainwater and/or the like taken into theintake duct 85 through the outside-air inlet port 86 together withoutside air is guided to flow downward along the upper surface of therainwater guide piece 140, flows downward from a front edge of therainwater guide piece 140 to a front edge of an upper surface of theduct bottom 88 d, and is then guided rearward and downward along theupper surface of the duct bottom 88 d. Then, the rainwater and/or thelike having reached a rear edge of the duct bottom 88 d passes throughthe draining hole 89, the draining pipe 90, the water discharging part91, and the discharge hole 92 in this order, and is then discharged tothe outside of the machine.

As described above, outside air having flowed into the intake duct 85 istaken, through the communication port 87 disposed downward of theelectrical unit 80, into a portion of the placement space S that isoutside of the intake duct 85, i.e., a portion of the placement space Sthat is inward from the intake duct 85 across the duct main piece 88.Thus, rainwater and/or the like having flowed into the intake duct 85together with the outside air is discharged through the draining hole 89located downward of the communication port 87. This can eliminate orreduce the possibility that rainwater and/or the like may give anadverse effect on the electrical unit 80 and/or the possibility thatrainwater and/or the like may be sucked into the intake pipe 72.Furthermore, even if a washing fluid enters the placement space S duringwashing of the construction machine A, malfunctioning or the like of theelectrical unit 80 caused by the washing fluid can be prevented, thanksto the partitioning wall 100 and the upper and lower hung screens 118and 124 for waterproofing, with which the electrical unit 80 is covered.

REFERENCE SIGNS LIST

A construction machine

S placement space

W cooling air path

72 intake pipe

80 electrical unit

85 intake duct

86 outside-air inlet port

87 communication port

1. A construction machine comprising: an engine; and a hood covering theengine, wherein a space inside the hood has a placement space in whichan electrical unit is placed and which communicates with outside air,and a distal-end opening of an intake pipe connected to an inlet port ofthe engine is disposed in the placement space to cause outside airsucked into the intake pipe due to a suction pressure occurred in theintake pipe to pass through the placement space to form a cooling airpath in the placement space.
 2. The construction machine according toclaim 1, wherein an intake duct having an outside-air inlet port throughwhich outside air is drawn and a communication port disposed downward ofthe outside-air inlet port is placed in the placement space, thedistal-end opening of the intake pipe is disposed upward of thecommunication port to form the cooling air path that is circuitous tocause the outside air drawn through the outside-air inlet port to passthrough the intake duct, to exit from the intake duct through thecommunication port, and to be drawn upward into the distal-end openingof the intake pipe, and the electrical unit is placed in a downstreamportion of the cooling air path, the downstream portion being locatedoutside of the intake duct.
 3. The construction machine according toclaim 2, wherein the placement space is a part of the space inside thehood, the part being partitioned by a partitioning wall serving as aninner wall placed in the space inside the hood and by a part of the hoodserving as an outer wall, the intake duct is shaped in a box which isvertically elongated in a top-and-bottom direction and which isconstituted by a duct main piece placed in the placement space and by apart of the hood serving as an outer side wall, the outside-air inletport is formed in the part of the hood serving as the outer side wall sothat the outside-air inlet port coincides with an upper portion of theduct main piece, the communication port is formed in a lower portion ofthe duct main piece, and the distal-end opening of the intake pipepenetrates through an upper portion of the partitioning wall to bedisposed in the placement space.
 4. The construction machine accordingto claim 2, wherein the communication port is opened toward theelectrical unit placed in the placement space.
 5. The constructionmachine according to claim 2, wherein the intake duct has a bottomincluding a draining hole for discharging rainwater having entered theintake duct through the outside-air inlet port.